Dynamic Evolution of Aluminum Coordination Environments in Mordenite Zeolite and Their Role in the Dimethyl Ether (DME) Carbonylation Reaction. (17th August 2022)

• Record Type: Journal Article
• Authors: Liu, Rongsheng; Fan, Benhan; Zhi, Yuchun; Liu, Chong; Xu, Shutao; Yu, Zhengxi; Liu, Zhongmin
• Is Part Of: Angewandte Chemie. Volume 134:Number 42(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-17
• Subjects: Aluminum Coordination -- DME Carbonylation -- Heterogeneous Catalysis -- Pyridine -- Zeolite; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202210658
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Part of tetrahedral framework aluminum in a protonic mordenite (HMOR) will convert geometry to distorted tetrahedral and octahedral coordination. High‐field 27 Al NMR data show that more framework Al atoms at T3 and T4 sites change geometry to nonframework structures than others. These nonframework Al species preferentially reside in the side pockets, which will decrease the accessibility of acid sites in the 8‐membered ring (MR) channel, impairing the dimethyl ether (DME) carbonylation reaction. The arisen octahedrally coordinated Al species are framework‐associated, which can be reverted into the zeolite framework. Herein, we find that a facile treatment with pyridine could force the octahedral coordination Al back into a tetrahedral environment, which could increase the number of available active sites and enhance the diffusion of DME, thus improving the reactivity (4 times) of the DME carbonylation reaction and prolonging the lifetime of catalysts. Abstract : When the protonic zeolite mordenite adsorbs pyridine, the nonframework aluminum species, preferentially located in the side pockets, can be forced back into the zeolite framework. This change increases the number of available active sites and enhances the diffusion of dimethyl ether (DME), hence improving the catalytic performances on the DME carbonylation reaction.